Rubber lining materials

Attempts to use rubber lining materials on non-alloyed steel resulted in significant failures. Today stainless steels and nickel... 

Table 2 Environmental resistance of common rubber lining materials...

Dry chlorine has a great affinity for absorbing moisture, and wet chlorine is extremely corrosive, attacking most common materials except HasteUoy C, titanium, and tantalum. These metals are protected from attack by the acids formed by chlorine hydrolysis because of surface oxide films on the metal. Tantalum is the preferred constmction material for service with wet and dry chlorine. Wet chlorine gas is handled under pressure using fiberglass-reinforced plastics. Rubber-lined steel is suitable for wet chlorine gas handling up to 100°C. At low pressures and low temperatures PVC, chlorinated PVC, and reinforced polyester resins are also used. Polytetrafluoroethylene (PTFE), poly(vinyhdene fluoride) (PVDE), and... 

Although performance curves are valuable in assessing classifier performance, frequently the cyclone overflow size analysis is used more than the d Q of the cyclone. In practice, clusters of cyclones (in parallel) are used to handle large capacities. Cyclones are manufactured in sizes ranging from 0.01 to 1.2 m in cyclone diameter, ie, the cylindrical section at the top (2,10). Capacities mn from 75 to 23,000 L/min. Materials of constmction vary widely. Rubber-lined or aH-polyurethane cyclones are used when abrasion is a problem. 

Rubber and Elastomers Rubber and elastomers are widely used as lining materials. To meet the demands of the chemical indus-tiy, rubber processors are continually improving their products. A number of synthetic rubbers have been developed, and while none has all the properties of natural rubber, they are superior in one or more ways. The isoprene and polybutadiene synthetic rubbers are duphcates of natural. 

These impellers are available in nearly any material of construction as well as rubber, rubber-lined, glass-lined. 

The standard polymers used for rubber linings consist of materials that are cross-linkable macromolecules which, on mixing with suitable reactants that form strong chemical bonds, change from a soft deformable substance into an elastic material. These polymers include natural rubber and its corresponding synthetic, c/s-polyisoprene, styrene-butadiene rubber, polychloroprene, butyl rubber, halogenated butyl rubbers, acrylonitrile-... 

Unless test coupons are produced alongside the lining, the only method of testing the vulcanisation state is with a hand hardness meter. A Shore A or IRHD meter is used for soft rubber linings and a Shore D meter for ebonites. The usual specification is that the hardness has to conform to 5° of the specified hardness. There is no quantitative non-destructive test for the strength of the bond between the lining and the substrate and so such tests are usually carried out in the laboratory on a sample prepared from the materials used. 

Originally, equipment was made largely from wood or gun-metal and often rubber lined. These materials give the lowest hazards from friction with explosives. Nowadays, improved standards of engineering and of design have made it possible to employ stainless steel and plastics in the construction of explosive machinery with considerable increase in mechanical efficiency. In this way not only can processes be carried out more rapidly, but the quantity of explosive present at any time is reduced, with consequent increase in overall safety. 

Other uses of titanium are in the construction of anolyte pipes, anolyte tanks, and dissolver and maturing tanks in the brine system. Here pure titanium cannot always be justified and instead rubber linings or polymeric materials are also used. Where the demand on uptime is rigorous, titanium-lined steel may be considered instead of rubber. 

The most widely used material for diazotization, dissolution, and the coupling vessels is rubber-lined steel. 

With reaction conditions of 200-225°F, 150—225 psi, and a palladium chloride-cupric chloride catalyst, MEK yields are 80-90%. The operating costs of the Wacker process for MEK (and acetone and several other petrochemicals as well) are relatively low. But the plant Is made of more expensive materials. Because of the corrosive nature of the catalyst solution, critical vessels, and the piping are titanium-based.(chats expensive ), and the reactor is rubber-lined, acid-resistant brick. ... 

Chemical pumps are available in a variety of materials. Metal pumps are the most widely used. Although they may be obtained in iron, bronze, and iron with bronze fittings, an increasing number of pumps of ductile-iron, steel, and nickel alloys are being used. Pumps are also available in glass, glass-lined iron, carbon, rubber, rubber-lined metal, ceramics, and a variety of plastics, such units usually being employed for special purposes. 

FIG. 10-192 Cost of shop-fabricated tanks in mid-1980 with Vr-in walls. Multiplying factors on carbon steel costs for other materials are carbon steel, 1.0 rubber-lined carbon steel, 1.5 aluminum, 1.6 glass-lined carbon steel, 4.5 and fiber-reinforced plastic, 0.75 to 1.5. Multiplying factors on type 316 stainless-steel costs for other materials are 316 stainless steel, 1.0 Monel, 2.0 Inconel, 2.0 nickel, 2.0 titanium, 3.2 and Hastelloy C, 3.8. Multiplying factors for wall thicknesses different from V4 in are ... 

The principal benefits of rubber lining are its excellent resistance to corrosive and abrasive chemicals and materials, e.g., acids, alkalies, salt water, slurries, sand, shot blast media, crushed ores etc. In addition to this, rubber linings provide other benefits including noise and vibration reduction, electrical and thermal insulation and product protection. 

Whilst carbon and stainless steels are commonly used materials of construction, increasing use is being made of non-metallic and rubber lined equipment. The selection of the material of construction should take into account the cases of the worst process conditions that may occur under foreseeable conditions and should be applied to all components including valves, pipe fittings, instruments and gauges. Both composition (e.g., chlorides, moisture) and temperature deviations can have a significant direct effect on the rate of corrosion. The operator should demonstrate that procedures are in place to ensure that potential deviations in process conditions such as fluid temperature, pressure and composition are identified and assessed in relation to the selection of materials of construction for piping systems. 

A wide range of rubbers are available for successful use as materials of construction and are applied in areas such as handling inorganic salt solutions where metals are unsuitable. The use of rubber linings is widespread in equipment such as tanks, pipes, and drums and most other critical chemical equipment. However, their use is limited to moderate temperatures, and they are generally suitable for use in abrasive duties. Some of the more commonly used plastics are PVC, PTFE and polypropylene. 

Materials of construction for ammonia are dependent on the operating temperature. Whilst mild steel may be used at ambient temperature, special costly steels are required at low temperatures to avoid embrittlement. Impurities in liquid ammonia such as air or carbon dioxide can cause stress corrosion cracking of mild steel. Ammonia is highly corrosive towards copper and zinc. Rubber lined steel construction is suitable for service at ambient temperature. 

Materials Handling Rubber lining for grabs, hooks and clamps. Wear resistant linings for chutes, hoppers storage bins etc. pulley rubber lagging for conveyor rollers. Soft natural rubber for wear resistance. Various rubber materials for roller coverings. 

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